Crashes in TouchExplorer on two finger swipe.

1. The logic for finding the active pointer was incorrect. The code was
   iterating over all pointer ids and taking the minimum, i.e. the pointer
   that first went down. The problem was that the down time for pointers
   that are not down was also considered (set to zero), thus sometimes we
   would consider the first pointer that went down to be a pointer that
   is not down at all. Now we are iterating only over the pointers that
   are down.

2. The batched events while waiting to see if the user is exploring or
   gesturing were added even if we were in touch exploration state at which
   point we do not have to batch. As a result we ended up having lefovers
   from a previous gesture when handling the delayed events and crash.

bug:10312546

Change-Id: I4728541ac12e4da4577d22e4314101dd169a52fb